On Fri, Oct 14, 2016 at 12:53:56PM +0200, Dmitry Vyukov wrote:
> KASAN stack instrumentation poisons stack redzones on function entry
> and unpoisons them on function exit. If a function exits abnormally
> (e.g. with a longjmp like jprobe_return()), stack redzones are left
> poisoned. Later this leads to random KASAN false reports.
>
> Unpoison stack redzones in the frames we are going to jump over
> before doing actual longjmp in jprobe_return().
>
> Signed-off-by: Dmitry Vyukov <[email protected]>
> Cc: Mark Rutland <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Andrey Ryabinin <[email protected]>
> Cc: Lorenzo Pieralisi <[email protected]>
> Cc: Alexander Potapenko <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: Ananth N Mavinakayanahalli <[email protected]>
> Cc: Anil S Keshavamurthy <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Masami Hiramatsu <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
>
> --
>
> Changes since v1:
> - leave kasan_unpoison_remaining_stack() intact
> - instead add kasan_unpoison_stack_above_sp_to()
> - rename kasan_unpoison_remaining_stack() to
> kasan_unpoison_task_stack_below()
>
> Changes since v2:
> - fix build by adding return type to kasan_unpoison_stack_above_sp_to
> (tested v2 with it, but forgot to git add)
I get build warnings with this patch applied and KASAN enabled:
mm/kasan/kasan.c: In function ‘kasan_unpoison_task_stack_below’:
mm/kasan/kasan.c:82:34: warning: passing argument 2 of ‘__kasan_unpoison_stack’
discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
__kasan_unpoison_stack(current, watermark);
^~~~~~~~~
mm/kasan/kasan.c:65:13: note: expected ‘void *’ but argument is of type ‘const
void *’
static void __kasan_unpoison_stack(struct task_struct *task, void *sp)
^~~~~~~~~~~~~~~~~~~~~~
mm/kasan/kasan.c: In function ‘kasan_unpoison_stack_above_sp_to’:
mm/kasan/kasan.c:92:27: error: called object ‘current_stack_pointer’ is not a
function or function pointer
const void *sp = (void *)current_stack_pointer();
^~~~~~~~~~~~~~~~~~~~~
In file included from ./include/linux/thread_info.h:54:0,
from ./include/asm-generic/preempt.h:4,
from ./arch/arm64/include/generated/asm/preempt.h:1,
from ./include/linux/preempt.h:59,
from ./include/linux/interrupt.h:8,
from mm/kasan/kasan.c:20:
./arch/arm64/include/asm/thread_info.h:69:24: note: declared here
register unsigned long current_stack_pointer asm ("sp");
Will
